[daip] [!5514]: aips - -SFL projection

[Eric Greisen]

Eric Greisen updated #5514
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                 Due: - Cleared - (was: 25 September 2014 06:46 PM)

-SFL projection 
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           Ticket ID: 5514
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/5514
           Full Name: Trisha L Ashley
               Email: trisha.ashley at gmail.com
             Creator: User
          Department: AIPS Data Processing
       Staff (Owner): Eric Greisen
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template Group: Default
             Created: 17 September 2014 11:35 PM
             Updated: 23 September 2014 07:32 PM
      Resolution Due: 30 September 2014 09:23 PM (7d 1h 51m)



I think you had better make the FITS file available to me plus 
your idea of what the coordinates should be.  I fear that the
people who wrote this "projection" do not know what they are doing.
-SFL (and other global projections) require a reference VALUE at 
the reference pixel to be 0 in declination or they become "oblique"
(rotated wrt to what you expect).  See pages 1081 and 1104-1105
in the WCS paper available at
      http://www.aoc/nrao.edu/~egreisen/AnAII.pdf
In fact, your basic desire to rotate the image does not make much
sense in this global coordinate.  If it is a small image and we can
get the coordinate header fixed, then we could re-grid into a true
projection (-SIN, -TAN, etc.) and then rotate.

Eric Greisen



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